著者

安田 喜憲

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.21, no.3, pp.255-271, 1982-10-31 (Released:2009-08-21)

参考文献数

43

被引用文献数

30 36

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Pollen analytical examination is carried out using the 32.2m core taken from a bottom of the Lake Mikata which is located in Fukui Prefecture (35°33′32″N.L.. 135°53′40″ E.L.). From the result of pollen analysis, 10 local pollen zones can be distinguished that is from lower upward MG (I, II, III), FG (I, II, III, IV, V), L and R. Each local pollen zone is sub-divided into several sub-zones.MG I and II zones (ca. 50, 000-41, 000B.P. years) are characterized by stabilized high values of Cryptomeria and Alnus suggesting cool and damper climate. This period is correlated with Port Talbot Interstadial in North America.MG III zone (ca. 41, 000-35, 000B.P. years) starts with short cold epoch which is defined by temporal increase of Tsuga. After this temporal cold epoch, frequency values of Cryptomeria shows unstability decreasing upward, on the other hand, Tsuga increases upward. This period is a transitional period from Interstadial to Pleniglacial.FG zone (ca. 35, 000-15, 000B.P. years) is marked by a decline of Cryptomeria with increase of Tsuga, Abies, Picea, Pinus Haploxylon and grass pollen like Artemisia, Thalictrum, Polygonum and Compositae indicating cold and dry climate. This zone is roughly subdivided into three characteristic periods.FG I zone (ca. 35, 000-31, 000B.P. years) is characterized by high values of Tsuga and other sub-alpine coniferous trees suggesting cold and dry climate.FG II zone (ca. 31, 000-24, 000B.P. years) is defined by increase of pioneer trees like Betula, Salix and Alnus replacing Tsuga. This zone occupies a relatively warm epoch and correlates with Plum Point Interstadial in North America.FG III, IV, V zones (ca. 24, 000-15, 000B.P. years) are dominated by Tsuga, Picea, Abies and Pinus Haploxylon indicating cold and dry climate. But the climate at FG IV zone (ca. 20, 000-18, 000B.P. years) shows wetter condition than those of FG III (ca. 24, 000-20, 000B.P. years) and FG V (ca. 18, 000-15, 000B.P. years) zones.L zone is defined by the decrease of Tsuga, Picea, Abies and Pinus Haploxylon with increase of Quercus and Alnus suggesting a climatic ameriolation. The opening of this zone is dated at 15, 000B.P. years.R zone is characterized by the sudden decrease of Tsuga, Picea, Abies and Pinus Haploxylon with the sudden increase of temperate trees like Fagus, Quercus, Juglans and Carpinus. Grass pollen also decreases suggesting the development of dense temperate broad-leaved forest under warm and moist climatic condition. The opening of this R zone is dated in 10, 000B.P. years.